Adolescence is widely understood to be a time of both increased risk-taking behavior (RTB) and heightened sensitivity to social contexts. The impact of social context on risk-taking may be especially relevant for early adolescents in the child welfare system (CWS). Early adolescent risk-taking has significant implications for long-term health outcomes, and CWS-involved youth may be particularly vulnerable to social context effects on risk-taking due to histories of peer rejection. The primary goals of the proposed research are threefold. First, we seek to better understand the interactions between risk-taking and social contexts in CWS-involved early adolescents by employing a novel paradigm (validated in our preliminary studies) that includes both behavioral and neuroimaging assessments of RTB across key social contexts: alone, with peers watching, and after social exclusion. Second, we aim to characterize longitudinal associations between neural and behavioral measures of RTB assessed in the laboratory and CWS-involved early adolescent concurrent and subsequent health-risking behaviors (HRBs), including drug use and high-risk sexual behavior, using estimates of brain functioning and connectivity as predictors of real-world outcomes. Third, we aim to explore specific effects of different profiles of adverse childhood experiences (ACEs) on these brain-behavior relationships. Individuals with CWS involvement have high levels of ACEs and high rates of drug abuse and other HIV risk behaviors, as well as related problems, but it is unclear exactly why this is the case. In this investigation, we propose to collect data from CWS-involved youth (N = 150) at two timepoints (age 11-13 and age 13-15 years). At T l we will collect both fMRI and behavioral data on RTB plus self-reports of realworid HRBs, and at T2 we will again collect self-reports of HRBs. In summary, this project will provide a comprehensive understanding of the neural foundations of CWS-involved early adolescent RTB and concurrent/subsequent vulnerability to HRBs associated with specific social contexts and with exposure to early childhood adversity, as well as expand our knowledge about the mechanisms linking childhood adversity with significantly greater engagement in HRBs.